b'Use of Advanced Core Neutronic Simulation Tools to Improve Mechanistic Models of SiC/SiC PerformancePrincipal Investigator: Nicholas Brown (University of Tennessee, Knoxville)Team Members/ Collaborators: Jacob Gorton (University of Tennessee, Knoxville; (ORNL); Benjamin Collins and Andrew Nelson (ORNL)significant deformation of the channel box. Research efforts have aimed at Figure 1. Cross-section of 10x10evaluating the performance of SiC/BWR fuel assembly model. SiC as a channel box in BWR fuel assemblies using advanced modeling tools with coupled thermal-hydraulics-to-neutronics capabilities. Project Description: The modeling tools used for this analysis are the coupled versions of MPACT and CTF within the Virtual Environment for Reactor Applica-tionsCore Simulator (VERA-CS) developed by the Consortium for Advanced Simulation of LWRs (CASL). MPACT is a deterministic Using VERA-CS toC hannel boxes surroundingreactor physics code, and CTF is a each fuel assembly in a boilingthermal hydraulics subchannel code. water reactor (BWR) make upThese computational tools have been obtain temperaturecoupled together by CASL to create a and fast neutrona significant portion of the zirconiumfeedback loop in which the tempera-flux distributions inin the reactor core. In line with thetures and densities calculated by CTF the channel box willgoals of the Accident Tolerant Fuelare used to update the cross sections provide accurate and(ATF) program, silicon carbide (SiC)used by MPACT, which then calculates high-fidelity boundaryfiber-reinforced, SiC matrix composite,the radial and axial power profile conditions that areor SiC/SiC, is being considered as ain the model. The power profile is useful in determiningpotential replacement for zirconiumfed back into CTF, and the process the feasibility of SiC/ as a channel box material. SiC/SiC hasiterates until convergence criteria SiC as a channel boxbeen shown to be significantly moreare met. Several coupled codes have material in BWRs. oxidation-resistant than zirconium,been developed for BWR application, so using SiC/SiC as a channel boxincluding TRACE/PARCS and PARCS/material may reduce the hydrogenPATHS, but one of the additional production in a BWR in the event ofbenefits of using VERA-CS is the level a severe accident. However, SiC/SiC isof fidelity provided by the output. known to undergo irradiation swelling,MPACT and CTF provide results and the nonuniform fast neutron fluxon a pin and subchannel resolved distribution in a BWR may lead to 162 2019|AFC ACCOMPLISHMENTS'